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2 years ago

13

75% of students is blank of 20 students

2 answers:

Ivan2 years ago

8 0

Answer: 15

Explanation: multiply 20 by .75

Ronch [10]2 years ago

7 0

Answer:

Step-by-step explanation:

You might be interested in

Find all the solutions for the equation:

Contact [7]

$2y^2\,\mathrm dx-(x+y)^2\,\mathrm dy=0$

Divide both sides by $x^2\,\mathrm dx$ to get

$2\left(\dfrac yx\right)^2-\left(1+\dfrac yx\right)^2\dfrac{\mathrm dy}{\mathrm dx}=0$

$\dfrac{\mathrm dy}{\mathrm dx}=\dfrac{2\left(\frac yx\right)^2}{\left(1+\frac yx\right)^2}$

Substitute $v(x)=\dfrac{y(x)}x$ , so that $\dfrac{\mathrm dv(x)}{\mathrm dx}=\dfrac{x\frac{\mathrm dy(x)}{\mathrm dx}-y(x)}{x^2}$ . Then

$x\dfrac{\mathrm dv}{\mathrm dx}+v=\dfrac{2v^2}{(1+v)^2}$

$x\dfrac{\mathrm dv}{\mathrm dx}=\dfrac{2v^2-v(1+v)^2}{(1+v)^2}$

$x\dfrac{\mathrm dv}{\mathrm dx}=-\dfrac{v(1+v^2)}{(1+v)^2}$

The remaining ODE is separable. Separating the variables gives

$\dfrac{(1+v)^2}{v(1+v^2)}\,\mathrm dv=-\dfrac{\mathrm dx}x$

Integrate both sides. On the left, split up the integrand into partial fractions.

$\dfrac{(1+v)^2}{v(1+v^2)}=\dfrac{v^2+2v+1}{v(v^2+1)}=\dfrac av+\dfrac{bv+c}{v^2+1}$

$\implies v^2+2v+1=a(v^2+1)+(bv+c)v$

$\implies v^2+2v+1=(a+b)v^2+cv+a$

$\implies a=1,b=0,c=2$

Then

$\displaystyle\int\frac{(1+v)^2}{v(1+v^2)}\,\mathrm dv=\int\left(\frac1v+\frac2{v^2+1}\right)\,\mathrm dv=\ln|v|+2\tan^{-1}v$

On the right, we have

$\displaystyle-\int\frac{\mathrm dx}x=-\ln|x|+C$

Solving for $v(x)$ explicitly is unlikely to succeed, so we leave the solution in implicit form,

$\ln|v(x)|+2\tan^{-1}v(x)=-\ln|x|+C$

and finally solve in terms of $y(x)$ by replacing $v(x)=\dfrac{y(x)}x$ :

$\ln\left|\frac{y(x)}x\right|+2\tan^{-1}\dfrac{y(x)}x=-\ln|x|+C$

$\ln|y(x)|-\ln|x|+2\tan^{-1}\dfrac{y(x)}x=-\ln|x|+C$

$\boxed{\ln|y(x)|+2\tan^{-1}\dfrac{y(x)}x=C}$

7 0

3 years ago

Until 2014, the mass of a kilogram was defined as exactly equal to the mass of a special

emmainna [20.7K]

Step-by-step explanation:

We have,

Diameter of cylinder, d = 39.2 mm

Radius, r = 19.6 cm

Height of the cylinder, h = 39.2 mm

It is required to find the surface area of this cylinder. The formula of the surface area of cylinder is given by :

$S=2\pi rh+2\pi r^2\\\\S=2\pi r(h+r)$

Putting all values we get :

$S=2\times\dfrac{22}{7}\times19.6\cdot(39.2+19.6)\\\\S=7244.16\ mm^2$

7 0

3 years ago

In the city where sonya lives, it rains and average of 8.05 centimeters each month last year.About how many centimeters of rain

erik [133]

In total it rained 96.6cm that year but on average it rained 100cm that year.
You would multiply 8.05 times the #of momths which is twelve.

7 0

3 years ago

Measurement is the use of numbers according to a standard true or false

Softa [21]

Answer:

True

Step-by-step explanation:

3 0

3 years ago

A square has a side length of 2.5 feet if the square is dilated by a factor of 2.5 what is the length of a side of the new squar

Anni [7]

Answer:

6.25

Step-by-step explanation:

You would multiply 2.5 by itself since you're dilating your side length.

6 0

3 years ago